Human or animal tissue is susceptible to many forms of damage. The damage can have many causes, including: non-complicated acute wounding, complicated chronic wounding, trauma, exercise related trauma and pathological damage.
An example of non-complicated acute wounding is a wound caused by surgery. Complicated chronic wounding may include wounds such as diabetic and venous ulcers, pressure sores and burns. Trauma wounds may include lacerations, contusions, incisions and blunt trauma such as bullet injuries. Exercise related trauma may occur to muscles, tendons and ligaments as a result of overuse, misuse and abuse. Pathological damage may cause joint problems, such as osteo-arthritis and rheumatoid arthritis.
Repair of damaged tissue involves regeneration of tissue cells which occurs naturally as a result of repair mechanisms in the human or animal body. Often the natural repair of damaged tissue can be a lengthy process or does not occur at all as a result of the debilitating effects of infection or permanent damage to the tissue repair mechanisms.
The time taken to repair damaged tissue can cause many related problems, such as infection or re-infection of the damaged tissue, prolonged pain, temporary or permanent disability, scarring or aesthetic embarrassment for the injured person. For athletes and animals, such as horses, tissue damage prevents participation in training or competitions.
Thus, it is advantageous to provide a device for treating damaged tissue that promotes faster tissue repair.
Dressings for promoting tissue repair have been known for many years. These dressings are coated with substances which are absorbed into the damaged tissue and actively encourage cellular regeneration and prevent infection. However, such dressings only provide a slight improvement in the speed of the healing process. In the case of serious trauma or large areas of wounding, such dressings can become ineffectual and, in some cases, create more damage, for example by preventing oxygen getting to the surface of the wound. In the case of muscle, ligament or tendon damage, such dressings have no therapeutic effect at all, except to act as a support to the damaged area whilst repair occurs naturally.
In recent years, electrical treatment of damaged tissue has become known as an effective method of treatment of damaged tissue. This method involves supplying electrical current to a treatment area (i.e. either directly to the external wound or to the surface of the skin near the damaged tissue). Electrodes are fixed to the treatment area and a current generating device is connected to the electrodes. Originally, these devices supplied current at a fixed amplitude ranging from 1 to 10 milliamps. It was found that supplying current via electrodes to the treatment area significantly improved the time taken to repair damaged tissue. However, supplying current at such levels can result in discomfort for the user of the device. Therefore, more recent developments have included supplying electrical current to the surface of a treatment area with a constant amplitude waveform typically having an amplitude in the range of 10 to 800 microamps. Electrical current in this range is commonly known as “micro-current” and the electrical stimulation it causes cannot generally be detected by a user of the device.
Some existing current generating devices for supplying current to electrodes fixed to a treatment area are described in PCT Publication Nos. 00/02622, 01/03768, 98/23326 and 98/40121 and U.S. Pat. No. 5,395,398. All of the current generating devices described in the aforementioned documents comprise a remote unit with attached electrodes. The electrodes must be fixed to the treatment area, typically with tape. Wires connect the electrodes to the current generating unit which is remote from the treatment area. Treatment with such devices requires specialist knowledge about the operation of the device and electrodes, including knowing where to locate the electrodes and how to connect them to the current generating device. This often necessitates frequent visits to clinics by a user of the device. Furthermore, there is the annoyance of having to carry a separate current generating unit. Generally, the user has to remain immobile whilst treatment is being carried out.
PCT Publication No. 94/22529 describes an elastic housing with electrodes sewn into specific positions which can be worn by a user. When the housing is worn by a user, the electrodes are in the correct anatomic position for optimal treatment of the tissue which is to be treated. A current generating unit is fixed to the housing by insertion into a small pocket on the housing. The current generating unit is connected to the electrodes and supplies current to the electrodes with a waveform chosen from a number of different waveforms by the user using a control pad on the generating unit. The waveforms have constant amplitude and constant frequency.
One problem with the device of PCT Publication No. 94/22529 is that it is difficult to obtain good conductivity between the electrode and the treatment area. Since the electrodes are sewn into the housing, they are not necessarily fixed to the treatment area appropriately even when the housing is correctly worn. The size and shape of the treatment area around which the housing is worn can vary from one user to another and even change shape or size over time. Furthermore, the treatment area itself can change its physical condition as it is repaired. In particular, levels of infection, temperature and pH may vary over time. Thus, a treatment programme chosen for a particular patient when treatment is commenced may need to be varied as treatment progresses. In addition, it has become apparent that supplying alternating current with a simple waveform having constant amplitude and frequency is not necessarily the most effective waveform for encouraging cell regeneration.
Accordingly, it is an aim of the present invention to provide an improved device for treating damaged tissue that increases the rate of cell regeneration.
It is a further aim of the present invention to provide an improved device for treating damaged tissue that integrates separate elements into a single device that can easily be applied to a treatment area by an uninformed user and which has improved conductivity between the electrodes and the treatment area.
It is a still further aim of the present invention to provide an improved device for treating damaged tissue that integrates separate elements into a single device that can easily be applied to a treatment area by an uninformed user and which adapts its programme of treatment according to the physical condition of the treatment area.